Leer at a playing error by the French (4)
I believe the answer is:
ogle
'leer at' is the definition.
(I've seen this before)
'a playing error by the french' is the wordplay.
'a playing error' becomes 'og' (I can't explain this - if you can you should give a lot more credence to this answer).
'by' means one lot of letters go next to another.
'the french' becomes 'le' ('the' in French).
'og'+'le'='OGLE'
Can you help me to learn more?
(Other definitions for ogle that I've seen before include "Gawp" , "John -, diarist, - Waugh, novelist" , "Look at amorously" , "Eye lewdly" , "Make eyes at" .)